SQLite xamarin iOS 本地数据库

using System;
using Cirrious.MvvmCross.Plugins.Sqlite;
using System.Linq;

namespace MobilePortalXApp.PCL
{
    public class DataService:IDataService
    {
        private readonly ISQLiteConnection _connection;
        public DataService (ISQLiteConnectionFactory factory)
        {
            _connection = factory.Create ("database.db");
            _connection.CreateTable<Notification> ();
            _connection.CreateTable<Announcement> ();
            _connection.CreateTable<NewsModel> ();
            _connection.CreateTable<Download1> ();
            _connection.CreateTable<Download2> ();
        }

        #region IDataService implementation

        public System.Collections.Generic.List<Notification> GetNotificationList ()
        {
            return _connection.Table<Notification> ().ToList ();
        }

        public void InsertNotification (Notification item)
        {
            int count = _connection.Table<Notification> ().Count();
            while (count>=10)
            {
                var firstItem = _connection.Table<Notification> ().First ();
                _connection.Delete (firstItem);
                count--;
            }
            _connection.Insert (item);
        }

        public void DeleteNotification (Notification item)
        {
            _connection.Delete (item);
        }



        public System.Collections.Generic.List<NewsModel> GetNewsList ()
        {
            return _connection.Table<NewsModel> ().ToList ();
        }

        public void InsertNews (NewsModel item)
        {
            _connection.Insert (item);
        }

        public void DeleteNews (NewsModel item)
        {
            _connection.Delete (item);
        }

        public void UpdateNews (NewsModel item)
        {
            _connection.Update (item);
        }

        public System.Collections.Generic.List<Announcement> GetAnnouncementsList ()
        {
            return _connection.Table<Announcement> ().ToList ();
        }

        public void InsertAnnouncements (Announcement item)
        {
            _connection.Insert (item);
        }

        public void DeleteAnnouncements (Announcement item)
        {
            _connection.Delete (item);
        }

        public void UpdateAnnouncements (Announcement item)
        {
            _connection.Update (item);
        }

        public System.Collections.Generic.List<Download1> GetDownload1List ()
        {
            return _connection.Table<Download1> ().ToList ();
        }

        public void InsertDownload1 (Download1 item)
        {
            int count = _connection.Table<Download1> ().Count();
            while (count>=10)
            {
                var firstItem = _connection.Table<Download1> ().First ();
                _connection.Delete (firstItem);
                count--;
            }
            _connection.Insert (item);
        }

        public void DeleteDownload1 (Download1 item)
        {
            _connection.Delete (item);
        }

        public System.Collections.Generic.List<Download2> GetDownload2List ()
        {
            return _connection.Table<Download2> ().ToList ();
        }

        public void InsertDownload2 (Download2 item)
        {
            int count = _connection.Table<Download2> ().Count();
            while (count>=10)
            {
                var firstItem = _connection.Table<Download2> ().First ();
                _connection.Delete (firstItem);
                count--;
            }
            _connection.Insert (item);
        }

        public void DeleteDownload2 (Download2 item)
        {
             _connection.Delete (item);
        }

        public void UpdateDownload1 (Download1 item)
        {
            _connection.Update (item);
        }

        public void UpdateDownload2 (Download2 item)
        {
            _connection.Update (item);
        }
        #endregion
    }
}